| Author | Message | ||
     Roderick Waite Frequent User Username: rodwaite Post Number: 242 Registered: 01-2012 |
Hello. I had the aircon system re-gassed when I fitted a new compressor 4 years ago. Everything fine until this year, using cooling rather than heating, now and then it wouldn't work. This got worse, and now it doesn't work at all. Put the switch to any position from low to defrost - a snatch of vent noise, but no fans and nothing happens. The compressor engages OK. The regulator can be full blue or full red. Nothing. Could this be as simple as re-gassing needed again, or more complicated? Thanks for thoughts. | ||
| Robert J. Sprauer Frequent User Username: wraithman Post Number: 555 Registered: 11-2017 |
Start with a manifold gauge set to get an indication of what is going on. It could be a few things. The system in general is Delco and parts readily available and most A/C system have the same set of components. The fact that the clutch is engaging at least shows there may be enough pressure in the system. | ||
| michael vass Frequent User Username: mikebentleyturbo2 Post Number: 587 Registered: 07-2015 |
Hi Rod When I had no gas in the heater still worked fine. Do you hear any flaps motors moving? Cheers Mike | ||
| Martin Taylor Experienced User Username: martin_taylor Post Number: 171 Registered: 07-2013 |
If the clutch is engaged you should have one cold pipe and one hot, if not the gas has leaked out or your compressor isn’t compressing (less likely), the system on these cars won’t speed up the fan until the air is cold enough so probably nothing else is wrong. | ||
| Jim Walters Frequent User Username: jim_walters Post Number: 272 Registered: 01-2014 |
Unplug the 44° sensor on the thermostat housing and see if it works then. This sensor controls an inhibit relay that prevents system operation until the coolant reaches 44°C. It is the single wire sensor on the thermostat and failure of this sensor is a common fault. SRH8505 SRC18015 SRE22493 NAC-05370 www.bristolmotors.com | ||
| Roderick Waite Frequent User Username: rodwaite Post Number: 243 Registered: 01-2012 |
Thank you everyone - very handy tips there! I'm a bit at sea with aircon, but a pal who knows what he's doing is coming over on Wednesday and we'll check through the list! On the phone he suspects the switch itself ... we'll see! Nice to know it's mostly standard parts though! Hi Mike - no heat either, and a very half-hearted buzz on switching that stops almost at once. | ||
| Jim Walters Frequent User Username: jim_walters Post Number: 273 Registered: 01-2014 |
Sorry it's a two wire plug on the 44° sensor, not a single wire. SRH8505 SRC18015 SRE22493 NAC-05370 www.bristolmotors.com | ||
| Roderick Waite Frequent User Username: rodwaite Post Number: 244 Registered: 01-2012 |
Right, Frank has been checking through the system and everything is OK and should work. But it doesn't and the problem therefore must lie with the control box - under the dash on the right hand (driver's) side.. Can anyone throw any light on what the most likely problem is with that? Thank you ... | ||
| Roderick Waite Frequent User Username: rodwaite Post Number: 245 Registered: 01-2012 |
More checking and burrowing about under the dash - couldn't find anything wrong. Everything pointed back to the 44 deg sensor. Unplugged it and it registered continuity on the meter - figured it must be reversed and should stop sending a signal at 44, not start. Aircon working fine with it unpolugged, hot and cold, vents working, fans working - who needs the sensor? Anyway, tracked one down at Flying Spares - over £100! Be here next week ... | ||
| Jim Walters Frequent User Username: jim_walters Post Number: 274 Registered: 01-2014 |
Like I said it is to prevent cold air being blown into the interior until the coolant temperature is warmed up enough to give you warm air. The continuity test you did is correct, the sensor is not reversed. The sensor operates the ACU isolation relay, which is energized until the coolant reaches 44°C then the sensor open circuits and disconnects the relay allowing ACU operation. SRH8505 SRC18015 SRE22493 NAC-05370 www.bristolmotors.com | ||
| Jim Walters Frequent User Username: jim_walters Post Number: 275 Registered: 01-2014 |
I should add that the 44°C sensor is always the first thing to check for non operating AC on 1978 and newer RR and Bentley vehicles. It's the most common failure and also the easiest to check, by unplugging the sensor you will know immediately if it is faulty. SRH8505 SRC18015 SRE22493 NAC-05370 www.bristolmotors.com | ||
| Roderick Waite Frequent User Username: rodwaite Post Number: 246 Registered: 01-2012 |
Hello Jim, and how right you were! Very hard to locate a new one though - and it isn't really, but modified from something else. The original is no longer available, which surprises me. The problem is that mine is not flange mounted, but screwed in like a spark plug - as I would expect. Oh well ... | ||
| Jim Walters Frequent User Username: jim_walters Post Number: 276 Registered: 01-2014 |
Rod, could I have your old one? I'm in the process of rebuilding these sensors but I am short of cores. I would be be happy to cover the cost of postage. Thanks. SRH8505 SRC18015 SRE22493 NAC-05370 www.bristolmotors.com | ||
| michael vass Frequent User Username: mikebentleyturbo2 Post Number: 588 Registered: 07-2015 |
Hi all , do you have a part number for the 44c switch? Cheers Mike | ||
| Roderick Waite Frequent User Username: rodwaite Post Number: 247 Registered: 01-2012 |
Hello Jim - you're welcome to the old one when we get the new one fitted -should be next week. I'll report then fow we got on. Don't know the part number Mike - it's not original (which is no longer available) but a modification to something else. The invoice will probably specify it when it arrives - I'll let you know then what they call it (Flying Spares). | ||
| Jim Walters Frequent User Username: jim_walters Post Number: 277 Registered: 01-2014 |
Thanks Rod, appreciate it. SRH8505 SRC18015 SRE22493 NAC-05370 www.bristolmotors.com |
